For example, in an ultrasonic bonding method for bonding a conductor of an electric wire to a terminal by ultrasonic vibration while applying pressure by a pressurization and vibration horn, the conductor of the electric wire is shaped into a rectangular shape in sectional view (for example, see PTL 1 to 5).
In the case of shaping a conductor of an electric wire into a rectangular shape in sectional view, as shown in FIG. 8, a conductor 4 of an electric wire 3 is arranged in a recessed groove portion 2 formed in a lower mold 1 and in this state, the conductor 4 of the inside of the groove portion 2 is pressed by an upper mold 5. Consequently, the conductor 4 of the electric wire 3 is pressurized by the lower mold 1 and the upper mold 5 and is shaped in a predetermined rectangular shape in sectional view.